X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/720d742f8e74acf1ade85a7d39c02fa5b9528b5a..e9f87b5b7df2e328d2e4196d276c0d96594c906b:/src/lalr.c

diff --git a/src/lalr.c b/src/lalr.c
index 36085271..c16c6f52 100644
--- a/src/lalr.c
+++ b/src/lalr.c
@@ -1,121 +1,111 @@
 /* Compute look-ahead criteria for bison,
-   Copyright (C) 1984, 1986, 1989 Free Software Foundation, Inc.
+   Copyright 1984, 1986, 1989, 2000, 2001  Free Software Foundation, Inc.
 
-This file is part of Bison, the GNU Compiler Compiler.
+   This file is part of Bison, the GNU Compiler Compiler.
 
-Bison is free software; you can redistribute it and/or modify
-it under the terms of the GNU General Public License as published by
-the Free Software Foundation; either version 2, or (at your option)
-any later version.
+   Bison is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
 
-Bison is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-GNU General Public License for more details.
+   Bison is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
 
-You should have received a copy of the GNU General Public License
-along with Bison; see the file COPYING.  If not, write to
-the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
-Boston, MA 02111-1307, USA.  */
+   You should have received a copy of the GNU General Public License
+   along with Bison; see the file COPYING.  If not, write to
+   the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
 
 
 /* Compute how to make the finite state machine deterministic; find
    which rules need lookahead in each state, and which lookahead
-   tokens they accept. */
+   tokens they accept.  */
 
 #include "system.h"
+#include "reader.h"
 #include "types.h"
-#include "state.h"
-#include "alloc.h"
+#include "LR0.h"
+#include "symtab.h"
 #include "gram.h"
 #include "complain.h"
 #include "lalr.h"
+#include "nullable.h"
+#include "derives.h"
+#include "getargs.h"
 
-extern short **derives;
-extern char *nullable;
-
+/* All the decorated states, indexed by the state number.  */
+state_t **states = NULL;
 
 int tokensetsize;
-short *lookaheads;
 short *LAruleno;
 unsigned *LA;
-short *accessing_symbol;
-char *consistent;
-core **state_table;
-shifts **shift_table;
-reductions **reduction_table;
+size_t nLA;
+
+static int ngotos;
 short *goto_map;
 short *from_state;
 short *to_state;
 
-extern void berror PARAMS ((const char *));
+/* And for the famous F variable, which name is so descriptive that a
+   comment is hardly needed.  <grin>.  */
+static unsigned *F = NULL;
+#define F(Rule)  (F + (Rule) * tokensetsize)
 
-static int infinity;
-static int maxrhs;
-static int ngotos;
-static unsigned *F;
 static short **includes;
 static shorts **lookback;
+
+
+/*---------------------------------------------------------------.
+| digraph & traverse.                                            |
+|                                                                |
+| The following variables are used as common storage between the |
+| two.                                                           |
+`---------------------------------------------------------------*/
+
 static short **R;
 static short *INDEX;
 static short *VERTICES;
 static int top;
-
+static int infinity;
 
 static void
 traverse (int i)
 {
-  unsigned *fp1;
-  unsigned *fp2;
-  unsigned *fp3;
   int j;
-  short *rp;
-
+  size_t k;
   int height;
-  unsigned *base;
+  size_t size = F (i + 1) - F(i);
 
   VERTICES[++top] = i;
   INDEX[i] = height = top;
 
-  base = F + i * tokensetsize;
-  fp3 = base + tokensetsize;
+  if (R[i])
+    for (j = 0; R[i][j] >= 0; ++j)
+      {
+	if (INDEX[R[i][j]] == 0)
+	  traverse (R[i][j]);
 
-  rp = R[i];
-  if (rp)
-    {
-      while ((j = *rp++) >= 0)
-	{
-	  if (INDEX[j] == 0)
-	    traverse (j);
-
-	  if (INDEX[i] > INDEX[j])
-	    INDEX[i] = INDEX[j];
-
-	  fp1 = base;
-	  fp2 = F + j * tokensetsize;
+	if (INDEX[i] > INDEX[R[i][j]])
+	  INDEX[i] = INDEX[R[i][j]];
 
-	  while (fp1 < fp3)
-	    *fp1++ |= *fp2++;
-	}
-    }
+	for (k = 0; k < size; ++k)
+	  F (i)[k] |= F (R[i][j])[k];
+      }
 
   if (INDEX[i] == height)
-    {
-      for (;;)
-	{
-	  j = VERTICES[top--];
-	  INDEX[j] = infinity;
-
-	  if (i == j)
-	    break;
+    for (;;)
+      {
+	j = VERTICES[top--];
+	INDEX[j] = infinity;
 
-	  fp1 = base;
-	  fp2 = F + j * tokensetsize;
+	if (i == j)
+	  break;
 
-	  while (fp1 < fp3)
-	    *fp2++ = *fp1++;
-	}
-    }
+	for (k = 0; k < size; ++k)
+	  F (j)[k] = F (i)[k];
+      }
 }
 
 
@@ -125,8 +115,8 @@ digraph (short **relation)
   int i;
 
   infinity = ngotos + 2;
-  INDEX = NEW2 (ngotos + 1, short);
-  VERTICES = NEW2 (ngotos + 1, short);
+  INDEX = XCALLOC (short, ngotos + 1);
+  VERTICES = XCALLOC (short, ngotos + 1);
   top = 0;
 
   R = relation;
@@ -135,87 +125,11 @@ digraph (short **relation)
     INDEX[i] = 0;
 
   for (i = 0; i < ngotos; i++)
-    {
-      if (INDEX[i] == 0 && R[i])
-	traverse (i);
-    }
-
-  FREE (INDEX);
-  FREE (VERTICES);
-}
-
-static void
-set_state_table (void)
-{
-  core *sp;
-
-  state_table = NEW2 (nstates, core *);
-
-  for (sp = first_state; sp; sp = sp->next)
-    state_table[sp->number] = sp;
-}
-
-
-static void
-set_accessing_symbol (void)
-{
-  core *sp;
-
-  accessing_symbol = NEW2 (nstates, short);
-
-  for (sp = first_state; sp; sp = sp->next)
-    accessing_symbol[sp->number] = sp->accessing_symbol;
-}
-
-
-static void
-set_shift_table (void)
-{
-  shifts *sp;
-
-  shift_table = NEW2 (nstates, shifts *);
+    if (INDEX[i] == 0 && R[i])
+      traverse (i);
 
-  for (sp = first_shift; sp; sp = sp->next)
-    shift_table[sp->number] = sp;
-}
-
-
-static void
-set_reduction_table (void)
-{
-  reductions *rp;
-
-  reduction_table = NEW2 (nstates, reductions *);
-
-  for (rp = first_reduction; rp; rp = rp->next)
-    reduction_table[rp->number] = rp;
-}
-
-
-static void
-set_maxrhs (void)
-{
-  short *itemp;
-  int length;
-  int max;
-
-  length = 0;
-  max = 0;
-  for (itemp = ritem; *itemp; itemp++)
-    {
-      if (*itemp > 0)
-	{
-	  length++;
-	}
-      else
-	{
-	  if (length > max)
-	    max = length;
-	  length = 0;
-	}
-    }
-
-  maxrhs = max;
+  XFREE (INDEX);
+  XFREE (VERTICES);
 }
 
 
@@ -224,139 +138,84 @@ initialize_LA (void)
 {
   int i;
   int j;
-  int count;
-  reductions *rp;
-  shifts *sp;
   short *np;
 
-  consistent = NEW2 (nstates, char);
-  lookaheads = NEW2 (nstates + 1, short);
+  /* Avoid having to special case 0.  */
+  if (!nLA)
+    nLA = 1;
 
-  count = 0;
-  for (i = 0; i < nstates; i++)
-    {
-      int k;
-
-      lookaheads[i] = count;
-
-      rp = reduction_table[i];
-      sp = shift_table[i];
-      if (rp && (rp->nreds > 1
-		 || (sp && !ISVAR (accessing_symbol[sp->shifts[0]]))))
-	count += rp->nreds;
-      else
-	consistent[i] = 1;
-
-      if (sp)
-	for (k = 0; k < sp->nshifts; k++)
-	  {
-	    if (accessing_symbol[sp->shifts[k]] == error_token_number)
-	      {
-		consistent[i] = 0;
-		break;
-	      }
-	  }
-    }
-
-  lookaheads[nstates] = count;
-
-  if (count == 0)
-    {
-      LA = NEW2 (1 * tokensetsize, unsigned);
-      LAruleno = NEW2 (1, short);
-      lookback = NEW2 (1, shorts *);
-    }
-  else
-    {
-      LA = NEW2 (count * tokensetsize, unsigned);
-      LAruleno = NEW2 (count, short);
-      lookback = NEW2 (count, shorts *);
-    }
+  LA = XCALLOC (unsigned, nLA * tokensetsize);
+  LAruleno = XCALLOC (short, nLA);
+  lookback = XCALLOC (shorts *, nLA);
 
   np = LAruleno;
   for (i = 0; i < nstates; i++)
-    {
-      if (!consistent[i])
-	{
-	  if ((rp = reduction_table[i]))
-	    for (j = 0; j < rp->nreds; j++)
-	      *np++ = rp->rules[j];
-	}
-    }
+    if (!states[i]->consistent)
+      for (j = 0; j < states[i]->reductions->nreds; j++)
+	*np++ = states[i]->reductions->rules[j];
 }
 
 
 static void
 set_goto_map (void)
 {
-  shifts *sp;
-  int i;
-  int symbol;
-  int k;
+  int state, i;
   short *temp_map;
-  int state2;
-  int state1;
 
-  goto_map = NEW2 (nvars + 1, short) - ntokens;
-  temp_map = NEW2 (nvars + 1, short) - ntokens;
+  goto_map = XCALLOC (short, nvars + 1) - ntokens;
+  temp_map = XCALLOC (short, nvars + 1) - ntokens;
 
   ngotos = 0;
-  for (sp = first_shift; sp; sp = sp->next)
+  for (state = 0; state < nstates; ++state)
     {
-      for (i = sp->nshifts - 1; i >= 0; i--)
+      shifts *sp = states[state]->shifts;
+      for (i = sp->nshifts - 1; i >= 0 && SHIFT_IS_GOTO (sp, i); --i)
 	{
-	  symbol = accessing_symbol[sp->shifts[i]];
-
-	  if (ISTOKEN (symbol))
-	    break;
-
 	  if (ngotos == MAXSHORT)
 	    fatal (_("too many gotos (max %d)"), MAXSHORT);
 
 	  ngotos++;
-	  goto_map[symbol]++;
+	  goto_map[SHIFT_SYMBOL (sp, i)]++;
 	}
     }
 
-  k = 0;
-  for (i = ntokens; i < nsyms; i++)
-    {
-      temp_map[i] = k;
-      k += goto_map[i];
-    }
+  {
+    int k = 0;
+    for (i = ntokens; i < nsyms; i++)
+      {
+	temp_map[i] = k;
+	k += goto_map[i];
+      }
 
-  for (i = ntokens; i < nsyms; i++)
-    goto_map[i] = temp_map[i];
+    for (i = ntokens; i < nsyms; i++)
+      goto_map[i] = temp_map[i];
 
-  goto_map[nsyms] = ngotos;
-  temp_map[nsyms] = ngotos;
+    goto_map[nsyms] = ngotos;
+    temp_map[nsyms] = ngotos;
+  }
 
-  from_state = NEW2 (ngotos, short);
-  to_state = NEW2 (ngotos, short);
+  from_state = XCALLOC (short, ngotos);
+  to_state = XCALLOC (short, ngotos);
 
-  for (sp = first_shift; sp; sp = sp->next)
+  for (state = 0; state < nstates; ++state)
     {
-      state1 = sp->number;
-      for (i = sp->nshifts - 1; i >= 0; i--)
+      shifts *sp = states[state]->shifts;
+      for (i = sp->nshifts - 1; i >= 0 && SHIFT_IS_GOTO (sp, i); --i)
 	{
-	  state2 = sp->shifts[i];
-	  symbol = accessing_symbol[state2];
-
-	  if (ISTOKEN (symbol))
-	    break;
-
-	  k = temp_map[symbol]++;
-	  from_state[k] = state1;
-	  to_state[k] = state2;
+	  int k = temp_map[SHIFT_SYMBOL (sp, i)]++;
+	  from_state[k] = state;
+	  to_state[k] = sp->shifts[i];
 	}
     }
 
-  FREE (temp_map + ntokens);
+  XFREE (temp_map + ntokens);
 }
 
 
 
-/*  Map_goto maps a state/symbol pair into its numeric representation.	*/
+/*----------------------------------------------------------.
+| Map a state/symbol pair into its numeric representation.  |
+`----------------------------------------------------------*/
 
 static int
 map_goto (int state, int symbol)
@@ -381,8 +240,8 @@ map_goto (int state, int symbol)
 	high = middle - 1;
     }
 
-  berror ("map_goto");
-/* NOTREACHED */
+  assert (0);
+  /* NOTREACHED */
   return 0;
 }
 
@@ -390,159 +249,150 @@ map_goto (int state, int symbol)
 static void
 initialize_F (void)
 {
-  int i;
-  int j;
-  int k;
-  shifts *sp;
-  short *edge;
-  unsigned *rowp;
-  short *rp;
-  short **reads;
-  int nedges;
-  int stateno;
-  int symbol;
-  int nwords;
-
-  nwords = ngotos * tokensetsize;
-  F = NEW2 (nwords, unsigned);
-
-  reads = NEW2 (ngotos, short *);
-  edge = NEW2 (ngotos + 1, short);
-  nedges = 0;
-
-  rowp = F;
-  for (i = 0; i < ngotos; i++)
-    {
-      stateno = to_state[i];
-      sp = shift_table[stateno];
+  short **reads = XCALLOC (short *, ngotos);
+  short *edge = XCALLOC (short, ngotos + 1);
+  int nedges = 0;
 
-      if (sp)
-	{
-	  k = sp->nshifts;
-
-	  for (j = 0; j < k; j++)
-	    {
-	      symbol = accessing_symbol[sp->shifts[j]];
-	      if (ISVAR (symbol))
-		break;
-	      SETBIT (rowp, symbol);
-	    }
+  int i;
 
-	  for (; j < k; j++)
-	    {
-	      symbol = accessing_symbol[sp->shifts[j]];
-	      if (nullable[symbol])
-		edge[nedges++] = map_goto (stateno, symbol);
-	    }
+  F = XCALLOC (unsigned, ngotos * tokensetsize);
 
-	  if (nedges)
-	    {
-	      reads[i] = rp = NEW2 (nedges + 1, short);
+  for (i = 0; i < ngotos; i++)
+    {
+      int stateno = to_state[i];
+      shifts *sp = states[stateno]->shifts;
 
-	      for (j = 0; j < nedges; j++)
-		rp[j] = edge[j];
+      int j;
+      for (j = 0; j < sp->nshifts && SHIFT_IS_SHIFT (sp, j); j++)
+	SETBIT (F (i), SHIFT_SYMBOL (sp, j));
 
-	      rp[nedges] = -1;
-	      nedges = 0;
-	    }
+      for (; j < sp->nshifts; j++)
+	{
+	  int symbol = SHIFT_SYMBOL (sp, j);
+	  if (nullable[symbol])
+	    edge[nedges++] = map_goto (stateno, symbol);
 	}
 
-      rowp += tokensetsize;
+      if (nedges)
+	{
+	  reads[i] = XCALLOC (short, nedges + 1);
+	  shortcpy (reads[i], edge, nedges);
+	  reads[i][nedges] = -1;
+	  nedges = 0;
+	}
     }
 
   digraph (reads);
 
   for (i = 0; i < ngotos; i++)
-    {
-      if (reads[i])
-	FREE (reads[i]);
-    }
+    XFREE (reads[i]);
 
-  FREE (reads);
-  FREE (edge);
+  XFREE (reads);
+  XFREE (edge);
 }
 
 
 static void
-add_lookback_edge (int stateno, int ruleno, int gotono)
+add_lookback_edge (state_t *state, int ruleno, int gotono)
 {
   int i;
-  int k;
-  int found;
   shorts *sp;
 
-  i = lookaheads[stateno];
-  k = lookaheads[stateno + 1];
-  found = 0;
-  while (!found && i < k)
-    {
-      if (LAruleno[i] == ruleno)
-	found = 1;
-      else
-	i++;
-    }
+  for (i = 0; i < state->nlookaheads; ++i)
+    if (LAruleno[state->lookaheadsp + i] == ruleno)
+      break;
 
-  if (found == 0)
-    berror ("add_lookback_edge");
+  assert (LAruleno[state->lookaheadsp + i] == ruleno);
 
-  sp = NEW (shorts);
-  sp->next = lookback[i];
+  sp = XCALLOC (shorts, 1);
+  sp->next = lookback[state->lookaheadsp + i];
   sp->value = gotono;
-  lookback[i] = sp;
+  lookback[state->lookaheadsp + i] = sp;
 }
 
 
-static short **
-transpose (short **R_arg, int n)
+static void
+matrix_print (FILE *out, short **matrix, int n)
 {
-  short **new_R;
-  short **temp_R;
-  short *nedges;
-  short *sp;
-  int i;
-  int k;
+  int i, j;
+
+  for (i = 0; i < n; ++i)
+    {
+      fprintf (out, "%3d: ", i);
+      if (matrix[i])
+	for (j = 0; matrix[i][j] != -1; ++j)
+	  fprintf (out, "%3d ", matrix[i][j]);
+      fputc ('\n', out);
+    }
+  fputc ('\n', out);
+}
 
-  nedges = NEW2 (n, short);
+/*-------------------------------------------------------------------.
+| Return the transpose of R_ARG, of size N.  Destroy R_ARG, as it is |
+| replaced with the result.                                          |
+|                                                                    |
+| R_ARG[I] is NULL or a -1 terminated list of numbers.               |
+|                                                                    |
+| RESULT[NUM] is NULL or the -1 terminated list of the I such as NUM |
+| is in R_ARG[I].                                                    |
+`-------------------------------------------------------------------*/
 
-  for (i = 0; i < n; i++)
+static short **
+transpose (short **R_arg, int n)
+{
+  /* The result. */
+  short **new_R = XCALLOC (short *, n);
+  /* END_R[I] -- next entry of NEW_R[I]. */
+  short **end_R = XCALLOC (short *, n);
+  /* NEDGES[I] -- total size of NEW_R[I]. */
+  short *nedges = XCALLOC (short, n);
+  int i, j;
+
+  if (trace_flag)
     {
-      sp = R_arg[i];
-      if (sp)
-	{
-	  while (*sp >= 0)
-	    nedges[*sp++]++;
-	}
+      fputs ("transpose: input\n", stderr);
+      matrix_print (stderr, R_arg, n);
     }
 
-  new_R = NEW2 (n, short *);
-  temp_R = NEW2 (n, short *);
+  /* Count. */
+  for (i = 0; i < n; i++)
+    if (R_arg[i])
+      for (j = 0; R_arg[i][j] >= 0; ++j)
+	++nedges[R_arg[i][j]];
 
+  /* Allocate. */
   for (i = 0; i < n; i++)
-    {
-      k = nedges[i];
-      if (k > 0)
+    if (nedges[i] > 0)
+      {
+	short *sp = XCALLOC (short, nedges[i] + 1);
+	sp[nedges[i]] = -1;
+	new_R[i] = sp;
+	end_R[i] = sp;
+      }
+
+  /* Store. */
+  for (i = 0; i < n; i++)
+    if (R_arg[i])
+      for (j = 0; R_arg[i][j] >= 0; ++j)
 	{
-	  sp = NEW2 (k + 1, short);
-	  new_R[i] = sp;
-	  temp_R[i] = sp;
-	  sp[k] = -1;
+	  *end_R[R_arg[i][j]] = i;
+	  ++end_R[R_arg[i][j]];
 	}
-    }
 
-  FREE (nedges);
+  free (nedges);
+  free (end_R);
 
+  /* Free the input: it is replaced with the result. */
   for (i = 0; i < n; i++)
+    XFREE (R_arg[i]);
+  free (R_arg);
+
+  if (trace_flag)
     {
-      sp = R_arg[i];
-      if (sp)
-	{
-	  while (*sp >= 0)
-	    *temp_R[*sp++]++ = i;
-	}
+      fputs ("transpose: output\n", stderr);
+      matrix_print (stderr, new_R, n);
     }
 
-  FREE (temp_R);
-
   return new_R;
 }
 
@@ -550,58 +400,42 @@ transpose (short **R_arg, int n)
 static void
 build_relations (void)
 {
+  short *edge = XCALLOC (short, ngotos + 1);
+  short *states1 = XCALLOC (short, ritem_longest_rhs () + 1);
   int i;
-  int j;
-  int k;
-  short *rulep;
-  short *rp;
-  shifts *sp;
-  int length;
-  int nedges;
-  int done;
-  int state1;
-  int stateno;
-  int symbol1;
-  int symbol2;
-  short *shortp;
-  short *edge;
-  short *states;
-  short **new_includes;
-
-  includes = NEW2 (ngotos, short *);
-  edge = NEW2 (ngotos + 1, short);
-  states = NEW2 (maxrhs + 1, short);
+
+  includes = XCALLOC (short *, ngotos);
 
   for (i = 0; i < ngotos; i++)
     {
-      nedges = 0;
-      state1 = from_state[i];
-      symbol1 = accessing_symbol[to_state[i]];
+      int nedges = 0;
+      int symbol1 = states[to_state[i]]->accessing_symbol;
+      short *rulep;
 
       for (rulep = derives[symbol1]; *rulep > 0; rulep++)
 	{
-	  length = 1;
-	  states[0] = state1;
-	  stateno = state1;
+	  int done;
+	  int length = 1;
+	  short *rp;
+	  state_t *state = states[from_state[i]];
+	  states1[0] = state->number;
 
-	  for (rp = ritem + rrhs[*rulep]; *rp > 0; rp++)
+	  for (rp = &ritem[rules[*rulep].rhs]; *rp >= 0; rp++)
 	    {
-	      symbol2 = *rp;
-	      sp = shift_table[stateno];
-	      k = sp->nshifts;
-
-	      for (j = 0; j < k; j++)
+	      shifts *sp = state->shifts;
+	      int j;
+	      for (j = 0; j < sp->nshifts; j++)
 		{
-		  stateno = sp->shifts[j];
-		  if (accessing_symbol[stateno] == symbol2)
+		  state = states[sp->shifts[j]];
+		  if (state->accessing_symbol == *rp)
 		    break;
 		}
 
-	      states[length++] = stateno;
+	      states1[length++] = state->number;
 	    }
 
-	  if (!consistent[stateno])
-	    add_lookback_edge (stateno, *rulep, i);
+	  if (!state->consistent)
+	    add_lookback_edge (state, *rulep, i);
 
 	  length--;
 	  done = 0;
@@ -612,8 +446,7 @@ build_relations (void)
 	      /* JF added rp>=ritem &&   I hope to god its right! */
 	      if (rp >= ritem && ISVAR (*rp))
 		{
-		  stateno = states[--length];
-		  edge[nedges++] = map_goto (stateno, *rp);
+		  edge[nedges++] = map_goto (states1[--length], *rp);
 		  if (nullable[*rp])
 		    done = 0;
 		}
@@ -622,25 +455,18 @@ build_relations (void)
 
       if (nedges)
 	{
-	  includes[i] = shortp = NEW2 (nedges + 1, short);
+	  int j;
+	  includes[i] = XCALLOC (short, nedges + 1);
 	  for (j = 0; j < nedges; j++)
-	    shortp[j] = edge[j];
-	  shortp[nedges] = -1;
+	    includes[i][j] = edge[j];
+	  includes[i][nedges] = -1;
 	}
     }
 
-  new_includes = transpose (includes, ngotos);
-
-  for (i = 0; i < ngotos; i++)
-    if (includes[i])
-      FREE (includes[i]);
-
-  FREE (includes);
-
-  includes = new_includes;
+  XFREE (edge);
+  XFREE (states1);
 
-  FREE (edge);
-  FREE (states);
+  includes = transpose (includes, ngotos);
 }
 
 
@@ -653,72 +479,113 @@ compute_FOLLOWS (void)
   digraph (includes);
 
   for (i = 0; i < ngotos; i++)
-    {
-      if (includes[i])
-	FREE (includes[i]);
-    }
+    XFREE (includes[i]);
 
-  FREE (includes);
+  XFREE (includes);
 }
 
 
 static void
 compute_lookaheads (void)
 {
-  int i;
-  int n;
-  unsigned *fp1;
-  unsigned *fp2;
-  unsigned *fp3;
+  size_t i;
   shorts *sp;
-  unsigned *rowp;
-  shorts *sptmp;		/* JF */
 
-  rowp = LA;
-  n = lookaheads[nstates];
-  for (i = 0; i < n; i++)
+  for (i = 0; i < nLA; i++)
+    for (sp = lookback[i]; sp; sp = sp->next)
+      {
+	int size = LA (i + 1) - LA (i);
+	int j;
+	for (j = 0; j < size; ++j)
+	  LA (i)[j] |= F (sp->value)[j];
+      }
+
+  /* Free LOOKBACK. */
+  for (i = 0; i < nLA; i++)
+    LIST_FREE (shorts, lookback[i]);
+
+  XFREE (lookback);
+  XFREE (F);
+}
+
+
+/*--------------------------------------.
+| Initializing the lookaheads members.  |
+`--------------------------------------*/
+
+static void
+initialize_lookaheads (void)
+{
+  int i;
+  nLA = 0;
+  for (i = 0; i < nstates; i++)
     {
-      fp3 = rowp + tokensetsize;
-      for (sp = lookback[i]; sp; sp = sp->next)
-	{
-	  fp1 = rowp;
-	  fp2 = F + tokensetsize * sp->value;
-	  while (fp1 < fp3)
-	    *fp1++ |= *fp2++;
-	}
+      int k;
+      int nlookaheads = 0;
+      reductions *rp = states[i]->reductions;
+      shifts *sp = states[i]->shifts;
+
+      /* We need a lookahead either to distinguish different
+	 reductions (i.e., there are two or more), or to distinguish a
+	 reduction from a shift.  Otherwise, it is straightforward,
+	 and the state is `consistent'.  */
+      if (rp->nreds > 1
+	  || (rp->nreds == 1 && sp->nshifts && SHIFT_IS_SHIFT (sp, 0)))
+	nlookaheads += rp->nreds;
+      else
+	states[i]->consistent = 1;
+
+      for (k = 0; k < sp->nshifts; k++)
+	if (SHIFT_IS_ERROR (sp, k))
+	  {
+	    states[i]->consistent = 0;
+	    break;
+	  }
 
-      rowp = fp3;
+      states[i]->nlookaheads = nlookaheads;
+      states[i]->lookaheadsp = nLA;
+      nLA += nlookaheads;
     }
+}
 
-  for (i = 0; i < n; i++)
+
+/*---------------------------------------.
+| Output the lookaheads for each state.  |
+`---------------------------------------*/
+
+static void
+lookaheads_print (FILE *out)
+{
+  int i, j, k;
+  fprintf (out, "Lookaheads: BEGIN\n");
+  for (i = 0; i < nstates; ++i)
     {
-      /* JF removed ref to freed storage */
-      for (sp = lookback[i]; sp; sp = sptmp)
-	{
-	  sptmp = sp->next;
-	  FREE (sp);
-	}
+      fprintf (out, "State %d: %d lookaheads\n",
+	       i, states[i]->nlookaheads);
+
+      for (j = 0; j < states[i]->nlookaheads; ++j)
+	for (k = 0; k < ntokens; ++k)
+	  if (BITISSET (LA (states[i]->lookaheadsp + j), j))
+	    fprintf (out, "   on %d (%s) -> rule %d\n",
+		     k, symbols[k]->tag,
+		     -LAruleno[states[i]->lookaheadsp + j] - 1);
     }
-
-  FREE (lookback);
-  FREE (F);
+  fprintf (out, "Lookaheads: END\n");
 }
 
-
 void
 lalr (void)
 {
   tokensetsize = WORDSIZE (ntokens);
 
-  set_state_table ();
-  set_accessing_symbol ();
-  set_shift_table ();
-  set_reduction_table ();
-  set_maxrhs ();
+  initialize_lookaheads ();
   initialize_LA ();
   set_goto_map ();
   initialize_F ();
   build_relations ();
   compute_FOLLOWS ();
   compute_lookaheads ();
+
+  if (trace_flag)
+    lookaheads_print (stderr);
 }